1. Field of the Invention
The present invention relates generally to variable speed transmissions and, more particularly, to a novel pin configuration and shifting arrangement for variable speed transmissions that utilize rings of shifting pins to vary drive ratios.
2. Description of the Related Art
Roughly 100 million bicycles are produced each year worldwide, and a derailleur is a current means to move all of them. An alternative concept for a power-shifting transmission first appeared in the early 1980s, which used a number of magnets to shift between gears. A pin displacement system used the polarity of magnets to shuttle concentric rows of pins in and out of gear. Further developments steered systems away from magnets and towards plastic pins. In early models, a moveable displacement system engaged rows of concentric pins. When a rider shifted gears, a linear movement deflection cam slid into position to engage a specified row; however, this system fell short because it lacked the gear shifting speed necessary to prevent pin head decapitations. This shortfall is remedied in the present invention.
U.S. Ser. Nos. 10/301,901 and 09/620,184, to the present inventor, first introduced solutions to these problems. These applications are incorporated herein as if they are fully rewritten. Testing of the inventions practicing the foregoing applications revealed a number of practical problems associated with an impingement of head pins with the ramp mechanism. It was discovered that mechanical failures would occur if there was no smooth engagement with the rotating pins and the ramp mechanism.
The present invention consequently provides an improved apparatus and method having benefits and characteristics not previously disclosed. The present invention utilizes less complex technology, yet it is a more reliable mechanical mechanism for shift urging.